The cost of fuels used for high temperature lime kilns has increased substantially over recent years. Once a nominal constituent of the final product price, fuel costs have become a substantial component of the cost of producing lime.
Additionally, lime manufacturers are faced with finding clean-burning fuels in order to minimize the complexity of building and operating off gas scrubbing pollution control equipment. It is well known that fuels such as oils and coal contain relatively high levels of sulfur. Additionally, if low grade (and therefore low cost) fuels are used, other contaminants such as metals like lead and chromium may be present. Producers must therefore strike a balance between fuel costs and pollution control costs.
It is also well known that industry generally is now subject to strict environmental laws controlling the handling and disposal of solid and liquid wastes which are considered noxious or are "listed" by regulating agencies. Wastes such as fluorine or chlorine containing hydrocarbons, hydrocarbon solvents, paints, sewage effluents and the like must generally be stabilized, packaged and transported to land fill facilities. These increasingly stringent laws may soon eliminate the possibility of disposing certain toxics or listed substances in land fills at all. Certain wastes which are not so listed may be disposal problems as well.
As used in the present application, the term "listed" refers to certain compounds which are set forth in U.S. environmental laws, for example the Resource Conservation and Recovery Act and U.S. Environmental Protection Agency regulations which require special handling and disposal because of the properties of these compounds, at certain concentrations, are hazardous to human health. As indicated below, stringent handling requirements imposed by these regulations can only be avoided by reacting the hazardous compounds so as to convert them to non-hazardous forms.
For the purpose of determining which chemical compounds are "listed" wastes as discussed herein, the provisions of the Resource Conservation and Recovery Act and the U.S.E.P.A. regulations are expressly incorporated by reference herein, and relied upon.
In light of these problems, the present invention relates to a composition made from waste products readily available from the waste disposal industry, which composition can contain certain of these listed materials or other nuisance waste materials but which, when compressed to a shaped solid and burned under controled conditions these materials are converted to innocuous compounds which are easily disposed of. The briquetted composition retains its structure during combustion so as to minimize formation of aerosol fly ash and capture volatilized sulfur, chlorine, fluorine and metal compounds which would otherwise escape. Since the composition is made from waste components which are available at very low or no cost, the briquetted composition can provide heat for a lime kiln, or other high temperature process, at very low cost. In fact, revenue may be realized by destroying the wastes.